The invention relates to a receptacle for securing a tool to a drive shaft of a power tool, a receiving opening being arranged on the tool or on the drive shaft, and a center axis of the drive shaft extending therethrough, the opening co-acting with a suitably formed securing section arranged in a raised fashion at the other one of the two elements, in order to form a positive engagement for transmitting a torque between the drive shaft and the tool.
The invention further relates to a suitable adapter that can be used, if the receiving opening and the securing section of the tool or of the drive shaft are not mated with each other.
A receptacle of the type mentioned at the outset is known from U.S. Pat. No. 4,980,976 which discloses a U-shaped angled cutting knife for severing adhesive beads in window panes of motor vehicles, the cutting knife having a star-shaped receiving opening in the shape of a regular polygon for securing an oscillatingly driveable drive shaft, the receiving opening being attachable to a suitably shaped securing section of the drive shaft. For securing the cutting knife after attaching to the securing section of the drive shaft with its receiving opening, a screw connection is provided, e.g. in form of a nut that can be screwed onto a screw neck of the drive shaft.
Such a receptacle for securing the tool to the drive shaft is provided in particular for oscillatingly driveable tools, in which a positive fit engagement between the drive shaft and the tool for the transmission of higher torques is required.
To this end, a plurality of tools are used, which cannot only be used as cutting knives, but also for other tasks, e.g. for sawing. By means of such oscillatingly driven saw blades, for example, precise cuts in car body working can be performed. For sawing in hard accessible locations, also finger-like tools are used, for instance in order to be able to perform special cuts in wood constructional work. Another field of application is grinding, as e.g. described in U.S. Pat. No. 4,920,702, or scraping.
It has turned out to be disadvantageous that the known receptacle for engagement between the tool and the drive shaft, in particular for such oscillatingly driven tools, tends to wear out after longer operation under high load.
It is a first object of the invention, to create an improved power tool having an improved receptacle for engagement between the drive shaft and the tool.
It is a second object of the invention, to create an improved receptacle in which the danger of wear out of the receiving opening is reduced and a transmission of high torques is guaranteed also in long-term operation.
It is a third object of the invention, to provide an improved power tool having a receptacle for a tool that is particularly suited for the transmission of high torque even when oscillatinly driven back and forth about a longitudinal axis.
It is a further object of the invention to provide a tool having an improved receptacle in which the danger of wear out of the receiving opening is reduced and a transmission of high torques is guaranteed also in long-term operation.
It is another object of the invention to provide a tool having an improved receptacle for securing to a power tool allowing the transmission of high torque even when oscillatinly driven back and forth about a longitudinal axis.
It is a further object of the invention to provide an adapter that can be used for the engagement between the tool and the drive shaft, if the shapes of the receiving opening and the securing section on the tool and on the drive shaft are not mated with each other.
These and other objects are achieved according to the invention by a receptacle with a receiving opening the shape of which is mated to a securing section of the drive shaft of the power tool, the securing section and the receiving opening having a plurality of bulges arranged at a radial distance from the longitudinal axis of the drive shaft, the bulges being, preferably, continuously connected by lateral flanks forming recesses between the bulges. The bulges may, preferably, be configured as rounded tips.
The object of the invention is in that way completely achieved.
By means of the new shape, namely, the occurrence of high torques and/or high surface pressures on any sharp edges like a regular polygon, used in prior art devices, is avoided. Instead, the torque is now mainly transmitted to the tool by lateral flanks forming recesses between the bulges.
By means of such a shape, lumped loads and, thus, high surface pressures are avoided, which occurred up to now in receiving openings in the form of regular polygons.
In that way, a reliable engagement between the tool and the drive shaft is created, by means of which extraordinarily high torques can be transmitted even with oscillating drives or with impact loads, without any danger that the receiving-opening or of the securing section may wear out.
In a preferred embodiment of the invention, the receiving opening has at least three, preferably six rounded tips pointing outwardly, with two adjacent tips being connected by a curved section, which extends to the center axis. Each pair of adjacent tips may be connected by lateral flanks extending from the pair of tips toward the longitudinal axis and converging in a common apex.
By means of such an embodiment, a particularly constant torque transmission is reached, which avoids high surface pressures.
In an additional improvement of the invention, the curved sections are configured in an arch-shaped, preferably in a circular arc-shaped manner.
According to another embodiment of the invention, the diameter ratio between a first diameter, determined by a circle on which the tips are arranged, and between a second diameter, determined by a circle on which the apexes are arranged, is approximately 4 to 6, preferably approximately 4.5 to 5.5, in particular approximately 5.1.
In another embodiment of the invention, the ratio between the first diameter ratio that is determined by the distance between two tips being opposite to each other and a radius of the arc-shaped rounded tips is approximately 30 to 46, preferably approximately 34 to 42, in particular approximately 37.
By means of these features, a particularly favorable torque transmission between the drive shaft and the tool can be guaranteed, without any danger of wearing out under oscillating load or impact load.
Preferably, the receiving opening is arranged on the tool and the securing section is arranged on the drive shaft.
In that way, a simple manufacture can be reached particularly by punching the receiving opening out of the tool.
According to another embodiment of the invention, the receptacle comprises a securing screw, which can be screwed into a threaded blind hole of the drive shaft.
In this way, the securing screw has preferably a head, which is dimensioned for being positioned onto the tool.
In an additional improvement of the invention, a clamping flange is provided, which has a central opening for receiving the securing screw and which has an annular protrusion on its side facing the drive shaft, the annular protrusion being dimensioned for positioning onto the tool.
By means of this measure, a good pressure for securing can be reached.
In an additional improvement of this embodiment, the clamping flange has a recess on its side facing the drive shaft, the recess being mated in its form and size with the securing section of the drive shaft.
In a further embodiment of the invention, the clamping flange is secured rotatably to the securing screw.
In that way, the handling is facilitated.
If the securing section is provided at the drive shaft of the power tool, the drive shaft has preferably a retaining flange at its tool side, the securing section being arranged at the side of the retaining flange facing the tool.
In that way, the tool can be screwed to the drive shaft, with the retaining flange serving as a supporting surface.
The object of the invention is further achieved by an adapter for clamping a tool, comprising a receiving opening being arranged on a drive shaft of a power tool, which has a securing section, wherein the shape of the receiving opening is not mated with the form of the securing section, having preferably the form of a regular polygon, wherein an adapter disk is provided on the first side of which a recess is provided, which is mated to the form of the securing section at the drive shaft in order to form a positive fit engagement with same, and on the second side of which a raised second securing section is provided which corresponds to the shape described before.
By using such an adapter, it is possible to use tools, that have already been provided with the receptacle according to the invention on power tools, with drive shafts that have a known securing section, e.g. the shape of a polygon. In that way, it is ensured that not all power tools already acquired by users need to be exchanged, if the new tools with the securing section according to the invention are to be used to this end.
In an additional improvement of this embodiment, the adapter comprises a clamping flange, which comprises a central opening for receiving a securing screw that can be screwed into the drive shaft, the clamping flange having an annular protrusion on the side of the tool, the annular protrusion being dimensioned for being positioned onto the tool.
To this end, the adapter disk comprises preferably a central opening for receiving a securing screw that can be screwed into the drive shaft.
The object of the invention is further achieved by an adapter for clamping a tool, comprising a receiving opening at a drive shaft of a power tool, which has a securing section of the shape according to the invention, wherein the form of the receiving opening is not mated with the form of the securing section, having preferably the form of a regular polygon, characterized by a securing section, which is mated with the form of the receiving opening of the tool and which is interspersed by a receiving opening of the shape according to the invention, which is mated with the securing section of the drive shaft.
By means of such an adapter it is made possible to clamp tools of common design that have a receiving opening of different shape, e.g. the shape of a regular polygon, onto a power tool with a drive shaft that has a securing section according to the invention.
In an additional improvement of this embodiment, the adapter comprises a clamping flange, which has a central opening for receiving a securing screw that can be screwed into the drive shaft, the clamping flange having an annular protrusion on the side of the tool, the annular protrusion being dimensioned for being supported on the tool.
In that way, an even distribution of power and a good pressure can be guaranteed when the tool is secured by means of a securing screw.
In an advantageous improvement of this embodiment, the clamping flange is secured rotatably to the securing screw.
In that way, the handling of the adapter is facilitated.
In another embodiment of the invention, the adapter comprises an adapter disk laterally projecting flange-like, on which the securing section is configured, wherein a spring element is arranged between the securing screw and the adapter disk, the spring element acting on the adapter disk.
By means of this measure, a detaching of the securing screw is prevented even after longer operation under the most different operation conditions, and a good pressure of the tool onto the drive shaft is guaranteed.
According to an alternative embodiment, the adapter has a securing screw, which can be screwed into a threaded blind hole of the drive shaft, the securing screw having a head that is dimensioned for being positioned onto the tool.
In that way, a clamping flange can be omitted and the function of same is taken over already by the securing screw itself. Also by this measure, an even distribution of power and a good contact of the tool onto the drive shaft is guaranteed.
It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention.